A while back I did a tutorial for making a business card using Inkscape. This will be basically the same, but use the Gimp instead.
A business card is a great way to represent yourself and your talent level (especially if you are a designer and you designed your own card). Creating a business card in the Gimp is fairly fast and easy.
Imageabstraction.com has a lot of great grunge backgrounds. Choose one you like and download it. I downloaded this one. © Darren Hester
Step 2 - New Image
Create a new image in the Gimp. Standard business card size is 2" x 3.5"
I don't recommend you create a 2x3.5" business card as it will be pixelated. I would scale up the image significantly to improve quality. Also; when printing your business card, you will have printer bleed. Go to the website of the company you wish to have print your business cards and find out what they require for bleed.
Step 3 - Insert the Background
Resize the background if necessary.
Step 4 - Darken the Background
Change layer mode to "Grain Merge."
Adjust the opacity till you like it.
Step 5 - Background for Text
Create a new transparent layer. Use the freehand select tool. Hold the CTRL key when doing that to get exact angles.
Fill in the area using the paint bucket. I filled it in white and lowered the opacity.
Step 6 - Background Text
Select the text (you will probably want to select feather for selection. I set mine to 4.
Find a grungy looking paint brush and erase your selection. (You will want to press the eye on the text selection so you can't see it. Make sure when you are erasing you are doing the background layer with the white paint). Erase somewhat artistically. You don't have to erase everything.
I like to apply jitter, then erase the background sides so it flows more.
Step 7 - Vignette
Use the gradient tool. Foreground to opacity.
Make sure black is your foreground and apply the gradient till the sides are more black. You will have to redo this step a few times to get every side.
Add your new text. You can optionally add drop shadows.
After having done this in both Inkscape and the Gimp, I would recommend that you use Inkscape to do this. The quality is always going to be easier in vector and it will be easier to go back and edit different steps.